U.S. Pat. No. 5,037,006 discloses a dispensing device for dispensing a foam. This known dispensing device comprises a manually compressible container for storing a liquid and air. The container comprises an opening in which a housing is fitted. In this housing, a liquid passage and an air passage are arranged which, during dispensing, are in communication with a dispensing passage which ends in a dispensing opening. The dispensing device furthermore comprises a valve body which, in a rest position, seals a mouth of the liquid passage and a mouth of the air passage. The valve body is a disc-shaped flexible element which is held at the circumference and is pressed against the mouths of the liquid passage and the air passage by means of a spring.
By compressing/squeezing the container, the pressure in the container is increased and thus the pressure in the liquid passage and the air passage. As a result of this elevated pressure, the valve body on the mouths of the air passage and the liquid passage gives way, and a stream of air from the air passage and a stream of liquid from the liquid passage come together in the dispensing passage. In the dispensing passage, the mixture of liquid and air is passed through a number of sieves in order to create a foam which is dispensed by the dispensing opening.
After the container has been squeezed, the container will essentially return to its original state, either by the elasticity of the container itself or by restoring means which are provided in order to return the container to its original state.
A drawback of the known dispensing device is the fact that the mixture of air and liquid is not optimum, as a result of which the quality of the foam is not satisfactory. In addition, the structure of the known dispensing device is complex and comprises many components, which makes production complicated. In addition, the air passage and the liquid passage are bendy, as a result of which the speed of the liquid and air stream decreases, which consequently also leads to a reduction in the quality of the foam.
Another drawback of the known dispensing device is that the ratio air/liquid between the quantities of air and liquid, which are dispensed by squeezing of the container, respectively, is fixed. For each desired air/liquid ratio a separate dispensing device has to be designed which is especially adapted for this ratio.